'75 W300 repair/mod project - Ol' Blue

I could fix that, but the results would be hard to hide. and I don't know if truck manifolds are worth it. :hmmm:
 
Dorman makes a reproduction of that truck manifold and it's available for $195 at Rock Auto. If I gave it the same clean-up treatment as I started to do to the original, they'd be pretty hard to tell apart. However, I can get a set of new stainless shorty headers for about $130 shipped, so I'm kinda leaning towards that option right now.

That crack is on the top center part, so it'd be visible just below the valve cover. Even if it could be fixed, the cost of shipping that pig across the country would eat into any savings I might gain by having it repaired.
 
gomopar440 said:
...... the cost of shipping that pig across the country would eat into any savings I might gain by having it repaired.
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I'm thinking it would probably be at least $30 each way.

Many times that I've made repairs to those type of cracks I discovered that the cause was a casting flaw. I repaired an HP manifold with a very similar crack a little over a year ago. As I was welding the crack I discovered the hidden flaw. Ended up with a hole the size of a dime. Took more time, but I saved the manifold. And the guy didn't care that it was visible. :dance:

Shorty headers look like they could be an almost direct replacement with very little mods. They're almost like a more efficient version of what you've got.
 
68R/T said:
Shorty headers look like they could be an almost direct replacement with very little mods. They're almost like a more efficient version of what you've got.
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That's pretty much what I'm thinking at this point.

I'll probably just set these stock manifolds back in the barn for now and keep an eye out for another one.
 
From what I've seen, the truck Bb manifolds seem to be almost as rare as HP manifolds. Not as desirable, but still rare.
 
The heads are off now and I was finally able to get a good look at the insides of the engine. The cam and lifters appear to be in good shape with no unreasonable wear. The pistons are all marked .030, so some PO has been in there for sure. The cylinders aren't scored in any way, they just don't have a cross hatch visible anymore. All the cylinders have built up carbon crud from the deck down into the bore about 3/8". Piston #8 appears to be in upside down in it's cylinder. The .030 stamping on it is upside down and at the bottom of that piston, while all the rest of the pistons have the .030 marking stamped right side up and near the top edges. The skies are getting dark again, so I put the tarp back onto the short block for now.

Right now the heads, pushrods, rockers and shafts are all on the bench in the barn for general cleanup. One extra step I've already done is to knock of some casting flash from the insides of the heads. that's so there aren't any big restrictions for the oil heading back to the pan.

I forgot to do a compression test first before I took the engine apart, so I'll proceed as if the valves need attention. I'm going to check the valve seat contact patch, and if needed lap the valves in so they all seal tight. I'll also check the stem to guide fit to make sure the guides aren't worn out.

When I pull the oil pan I'll also pull the pistons and rods out. Then I'll be able to run a hone through the cylinders and give them a decent cross hatch. I'll need to pick up some rings before it goes back together. When I put it all back together I'll be able to put the #8 piston (and all the other pistons) in correctly.
 
More important than the .030 marking, look for a small "V" notch at the outer edge on the top of the piston. That notch should be towards the front. And when you pull that rod cap off check to make sure the bearing "lock" is pointing towards the opposite bank. It may be possible that the piston is installed wrong, or, the entire rod & piston combo are wrong. If the rod is wrong, look very closely for any signs of scoring on the lower ends of both 7 & 8, and the outer edges of those journals.
 
I was planning on checking the rod orientation when I drop the oil pan. When I saw that piston was upside down, that was one of the first things I started wondering about as well.
 
There hasn't been any progress in the last two days due to putting up a sheep fence around our 5 acre property. Got a little ways to go on that still, so the next day or two doesn't look any better for having any time to work on the truck.


Payday is on Thursday, so I hope to be done with all this non truck stuff by then. First thing I need to do is drop off the flywheel and get it resurfaced. I also need to order a new valley pan intake gasket for sure since I forgot to order one when I was getting the gaskets for this engine. Rings for the .030 pistons will have to wait to get ordered until I get them out and can measure them for thickness. A reproduction manifold to replace the cracked one would cost about $200, and used replacements are nearly impossible to find (or trashed like mine) around here. As a result I'm most likely going to pick up a set of stainless shorty headers to replace the factory manifolds.


I already have a cylinder hone, so I just need to get the pistons out of the way before I can use it on the block. The oil pan and timing cover both still need to get cleaned up and then painted gunmetal grey. The damper will get painted satin black and the timing marks on it will get filled in with white paint for contrast.
 
After getting the local welding guru to look at it, he suggested that it could possibly be brazed, except that he didn't think this particular manifold was savable. He pointed out a ton of small checks in the area above the double center port that looked kind of like a sunburst type pic of a sunset. FML. The welder guy is actually fond of Mopars and had quite a few big block engines, cars and parts laying around, just none with that style of truck manifold. He referred me to another local guy that was also a Mopar guy. That guy was only a few blocks away, so I went over to his place to see if he might have the manifold I needed. No such luck. Plenty of big block pass car manifolds around, but none like mine. At this point my two best leads fizzled out and the idea of repairing the cracked one has been vetoed by a welding expert. Looks like I'll have to buy those shorty headers after all.
 
Brazing cast is a lot trickier than with a stick. But on a manifold it would be more ideal because of heat expansion. I repair cast with a nickle rod and I use a stitching technique. I weld about an inch at a time and never allow it to get too hot that I can't touch it about 2 inches from my weld. It's a very slow process, but it's worked for me on many things with repairs that have lasted for years.

I've even done some weird stuff. On my 440 Volare waGOON I needed to extend the drivers side exhaust outlet about 4 inches to clear the steering. I cut off the flange and inserted a piece of black pipe. After 10 years of driving it like an old lady, :liar: still no leaks.
 
I let another welding shop take a look at the manifold today for a second opinion. Long story short, they tried to weld it up with nickle rod and immediately blew a crater halfway through the casting. They stopped there rather than keep trying and possibly destroying the manifold completely. Ok, shorty headers it is I guess.

The same machine shop that attempted the manifold also resurfaced the flywheel for me at the same time. It cleaned up fine and should be good to go for quite a while (as long as I don't drive stoopid...:toot:).

Afterwards I stopped by that little hole in the wall JY and picked up the two fenders and the hood for $75. Before I left I spied a factory oil gauge still sitting in a loose instrument cluster. Got that for $10 and he threw in all the little plastic dash light sockets with it.

BTW: I named the color scheme on those new old parts "Bananaflage".:banana: Think of how a half overripe banana looks, black and yellow with some funky moldy colors going on and you're right there. I'll get some pics of them when it's not raining out (again).:rolleyes:

EDIT: In addition to the spark plugs I picked up locally today, I just ordered the intake valley pan, distributor cap and spark plug wires from RA. I also ordered the stainless shorty headers so I can finally put that decision behind me now.
 
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gomopar440 said:
.... they tried to weld it up with nickle rod and immediately blew a crater halfway through the casting.
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Too much amperage. :naughty: Most people don't realize that stock cast manifolds are only about 1/8 in. thick. Welding manifolds is kind of an art. I'm not bragging because over the years I've ruined more than one. :doh:
 
68R/T said:
Too much amperage. :naughty: Most people don't realize that stock cast manifolds are only about 1/8 in. thick. Welding manifolds is kind of an art. I'm not bragging because over the years I've ruined more than one. :doh:
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Years ago I did a good bunch of work in a shop next to a local welding shop. The Dad there - a bit of a local legend - did a shitload of marine welding. He said he preferred gas welding on cast manifolds and any thin cast material and that the trick to success was to preheat them and to control the cooling-down period.
I know very, very little about welding cast but it seemed to make sense. ?
He's long since retired from day-to-day work but I pop in to visit him once in a while. Nice to talk with guys with the experience he has. No one else in the shop - including his son who is a good friend - can do half of what the old man could do... :(
 
The preferred method for gas welding was to place the piece in heated sand. It makes life easier too if you can do this for arc welding. Then you can weld continous rather than stitching.
 
@68R/T: I may just ship that manifold out to you to give it a shot someday. I over spent my truck budget this month again, so it'll be a little while before I'm ready to drop it in the mail. :shifty:

Those shorty headers will fit the bill for now anyway. I'd actually prefer traditional long tube headers, mainly because of the torque advantage they have over shortys. However I couldn't find any that I liked, and could afford at the moment. Going to long tubes will also require completely redoing the exhaust pipes and mufflers, while the shortys should be pretty close to working with the existing pipes I have on the truck now.
 
gomopar440 said:
@68R/T: I may just ship that manifold out to you to give it a shot someday. I over spent my truck budget this month again, so it'll be a little while before I'm ready to drop it in the mail. :shifty:
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Let me know when you're ready, I'll message you my addy. If the hole that the other guy blew in is smaller than a nickle, I can fix that too. I can fix larger ones but it takes a longer time and gets a little ugly. :doh:
 
It's more of a crater than a hole. It's about 1/4" in diameter and 1/8" or less deep as far as I can tell by looking at it.
 
If it sprouted a crater that may just be the afore-mentioned casting flaw. :hmmm:
 
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